STUDY DESIGN: Case-control and reliability study. OBJECTIVES: To compare foot and ankle characteristics between individuals with and without patellofemoral pain syndrome (PFPS) and to identify reliable weight-bearing foot and ankle measurements for use in future research on PFPS. BACKGROUND: PFPS is a common presentation to sports medicine and orthopaedic clinics. Characteristics of the foot and ankle are often linked with PFPS development, although evidence to support this link is equivocal and there is a lack of consensus on how best to evaluate these characteristics. METHODS: A variety of weight-bearing foot and ankle measurements were evaluated by 3 raters of varying experience in 20 individuals with PFPS and 20 controls matched by age, sex, height, and body mass. Between-group comparisons were made for each measurement using data from an experienced podiatrist blinded to group assignment of the participants. Intrarater and interrater reliability was compared between all measurements using the first 15 participants from each group. RESULTS: Between-group comparisons showed that the individuals in the PFPS group had a more pronated foot posture when assessed by the foot posture index and longitudinal arch angle, and for all measurements relative to subtalar joint neutral. Foot posture index, normalized navicular drop, and calcaneal angle relative to subtalar joint neutral measurements also possessed high reliability in both groups when used by experienced raters. Reliability was not influenced by rater experience or the presence of PFPS for relaxed-stance foot posture measurements. Both tester inexperience and the presence of PFPS reduced reliability for all measurements of foot posture relative to subtalar joint neutral and measurement of weight-bearing ankle dorsiflexion. CONCLUSION: The foot posture index, normalized navicular drop, and calcaneal angle relative to subtalar joint neutral are all reliable and sensitive to group differences when used in a population with PFPS. Individuals with PFPS possess a more pronated foot posture and increased foot mobility compared to controls. Prospective evaluation of these measurements is now required to determine whether they contribute to the development of PFPS. J Orthop Sports Phys Ther 2010;40(5):286-296, Epub 12 April 2010. doi:10.2519/jospt.2010.3227.